prometheus/prompb
..
buf.lock
buf.yaml
custom.go
README.md
remote.pb.go
remote.proto
types.pb.go
types.proto

The compiled protobufs are version controlled and you won't normally need to re-compile them when building Prometheus.

If however you have modified the defs and do need to re-compile, run make proto from the parent dir.

In order for the script to run, you'll need protoc (version 3.12.3) in your PATH.